It is known that the combustion of sludge originating from sewage-purification stations can be effected in a furnace for incinerating household refuse. However, this combustion gives rise to problems which are difficult to overcome, in particular due to the high moisture content of the sludge and to the need for ensuring a regular and homogeneous introduction of the sludge into the incineration furnace.
There currently exist various methods and devices which are used for introducing sludge into furnaces for incinerating household refuse, among which there may be mentioned, in particular:
the introduction of sludge to the feed chute receiving the refuse with the aid of a feed system, for example of the Archimedes screw type. Such a solution gives rise to heterogeneities in the concentration of the sludge in the region of the feed screw, which is translated into poor combustion;
the prior conditioning of the sludge to form granules with a low moisture content which are introduced into the combustion chamber of the incineration furnace at the same time as the household refuse, in the feed hopper of the latter. This known technique requires a heat-drying operation which is costly in terms of energy and investment, not to mention handling, treatment and transport of the sludge, which, of course, increases the cost price and can be the cause of pollution for the operating staff;
the spraying of the sludge onto the combustion grid of the incinerator with the aid of a feed system which breaks up this sludge which is to be spread over the combustion grid. The difficult problem to overcome here is that of calibrating the sludge and spreading it over the surface of the combustion grid.